Yu Hai, a second-year high school student, and Bai, a third-year junior high school student, have been childhood friends who attended piano classes together since they were little. Bai's personality is completely different from Yu Hai's carefree and boyish nature. Since childhood, Bai has been adorably girlish with exceptional piano skills! Yu Hai regards Bai as his younger sister, but one day, she suddenly kisses him... She also says, "I like you"...